Microsoft's Xbox 360 console contains illegally used technology, Lucent alleged last week - and filed a patent infringement lawsuit against the software giant to back up its claim. It is seeking unspecified damages and a jury trial.

The complaint, filed with the US District Court in San Diego on 28 March, alleges the Xbox 360's MPEG 2 decoder uses techniques outlined in patent number 5,227,878, which is owned by Lucent and details an system for "adaptive coding and decoding of frames and fields of video". Microsoft, said Lucent's suit, does not have permission to use this technology.

Lucent said it had notified Microsoft of the alleged infringement, but the console company did not suspend sales of the Xbox 360 or, presumably, offer to license the technology for a royalty acceptable to Lucent.

Lucent sued Microsoft in 2003 for infringement of the same patent, but the software giant was able to persuade the judge to throw out the case because of a typo in the patent's wording. Lucent has since edited the text, and is now having another go at prosecuting Microsoft. ®